Clinical virus isolates from a patient with HIV-1 infection can be important in understanding how neutralizing antibody (NA) titers evolve over the course of the disease. Sequential serum samples taken from five patients at six month intervals before and against autologous virus isolates changed over time. A frozen aliquot of virus adapted to H9 cells from five different patients was obtained to grow a virus pool sufficient for a number of NA assays. These pools were titered in Molt-3 cells to determine the dilution of virus necessary for NA tests. Six to ten sequential serum samples from each patient were heat-inactivated, and tested against the autologous strain of virus. In the four patients studied, we did not see a difference in NA titer in the sera before and after virus isolation. A second isolate from some of the patients was received and they were grown and are being titered in our assay system. Also, testing against other strains of virus will be done.